31 6 BOTANICAL GAZETTE [OCTOBER 



whose problematical relationship to the Myxomycetes has been the subject 

 of considerable discussion. The two groups of Acrasieae (Guttulinaceae 

 and Dictyosteliaceae) agree in that the vegetative individuals assume the 

 form of amoeboid cells which never pass through a swarm cell condition, and 

 in that the individuals during the fructifying period unite to form colonies 

 (pseudoplasmodia); but they differ widely in the general character and struc- 

 ture of their fructifications, the Guttulinaceae showing little or no differentia- 

 tion, and the Dictyosteliaceae considerable differentiation both in structure 

 and function. In certain forms two types of division were observed ; one in 

 the young individuals shortly after germination, occupying a number of hours 

 and accompanied by prolonged nuclear changes that resemble karyokinetic 

 division ; the other during the subsequent active amoeboid condition, resem- 

 bling direct division and taking place usually within a few minutes. In a dis- 

 cussion of the sytematic relations of the Acrasieae, the author states that 

 there can be no question as to the common origin of the Myxomycetes and the 

 Acrasieae, but that when the two groups are carefully compared it appears 

 unlikely that the former have been derived directly from the latter, since the 

 amoeboid stage is in reality the only feature strictly comparable. The families 

 and genera recognized are as follows : Sappiniaceae : Sappinia Dangeard (i 

 sp.) ; Guttulinaceae: Gnttidinopsis Olive (3 spp.), Guttulina Cienkowsky(4 

 spp.); Dictyosteliaceae: Acrasis Van Tieghem (i sp.), BicfyosU/tum Breield 

 (7 spp.), Polyspho7idyHum Brefeld (3 spp.), Coenonia Van Tieghem (i sp.). 

 —J. M, C, 



One of Dr. Engler's latest conceptions, which is already beginning to 

 find concrete realization, is a vast botanical garden, which shall display the 

 characteristic plant formations of the world. The underlying idea in Dr. 

 Engler's scheme is floristic rather than ecological, although typical edaphic 

 plant societies find representation. He had already outlined in detail his plan 

 for an alpine garden — this has received very favorable mention, and may be 

 referred to somewhat fully in these pages at another time. In a pamphlet" of 

 nearly a hundred pages Dr. Engler gives a plan of the garden and states his 

 ideas in full as to the floristic subdivision of North America north of Mexico. 

 The four chief divisions are Arctic, Subarctic, Atlantic, and Pacific. The 

 Arctic division is like that of Europe and is not treated. Subarctic North 

 America is subdivided into eastern, central, and western districts (Bezirke). 

 Atlantic North America is subdivided into four provinces; lake, Mississippi 

 and Alleghany deciduous forest, south Atlantic evergreen, and prairie. Pacific 



"Engler, Dr. Ai>olf, Die pflanzengeographische Gliederung Nordamerikas 

 erlautert an der nordamerikanischen Anlage des neuen Koniglichen botanischen 

 Gartens zu Dahlem-Steglitz bei Berlin. Separate reprint from Notizblatt Konigl. Bot. 

 Gart., Appendix IX. Svo. pp. iv-f- 94, with plan and distribution map. Leipzig: Wil- 

 helm En^Iemann. 1002. M 2,aq, 





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